Multicolor-screen for use with lenticulated films



Fei; 11, 1936. E. G EEEEE ER 2,030,447

Patented Feb. 11, 1 936 MUL'rIcoLonsoREEN Fon USE wrm LENTICULATED FILMS yEdgar Gretener, Berlin-Siemensstadt, Germany,v assigner to Opticolor Aktiengesellschaft, Glarus, Switzerland, a corporation of Switzerland Application January 20, 193,4, Serial No. 707,531

. In Germany January 20, 1933 1 claim. (c1. azi-16.4)

This invention relates to multicolor screens for use with lenticulated iilms. Its purpose is to increase the luminosity of such screens without lowering the saturation of the colors.

The new screens are characterized by the fact that the zone of greatest length is colored red. When the zones, as being, for instance, limited by circular lines, are of no 'definite lengths, the average lengths are employed for choosing the zone which is to'be colored red. Some examples of the new screensl are represented in the figures.

The screen in Figure 1 consists of the vthree zones |2, 3 which are. colored green, red and blue, the central one being red. Small strips 4 and'5 impermeable to light are arranged between the zones of the sceen. These zones as well as the segments 6 and 'l concealing the lateral borders of the screen'serve for lowering the diffusion of light between the different zones. The screen is held `by' the yring 8 bearing at two opposite spots the pins 9 and III which serve for securing an exact position of the screen with-respect to the lenticular elements of the photographiclnn 'I'he zones of this screenare' limited partly by straight and partly by curved lines.

The screen represented in Figure 2 is similar to that of Figure 1, the only difference being that the two marginal zones I and -3 are made somewhat smaller by using the diaphragms Il through I4. 'lhus for 'the lateral zones two equal exposures are secured over their whole breadths.

The eiciency of the screen represented in Figure 3 is similar to-that of the screen of Figure 2 in consequence of'the fact that the diaphragms I5 and I6 are so shaped that the zones I and 3 are taperingtowa'ds their ends. Thus the screen y has the highest luminosity combined with a good resolving of colors, as the centers of gravity have equal distances from each other which distancesv are equal about to one third of the diameter of the whole screen. This form of the screen is -a good means for preventing' the light diffusions from disturbing the saturation of the colors.

- In all the described screens the longest zone which is the central one is colored red. The ad? vvantage of -such an arrangement of the colors is seen from the following explanations.

Till now the central zone was green. As it was the longest one its breadth was only about lone fourth till one third the breadth of the lateral zones, which fact was in accordance with the spectral sensibility of the emulsion layers. Now

the diffusionof lightin the photographic layer which takes place as well as during the exposure and during the-projection has the consequence that veach part of the photographic layer is also inuenced by such light which had passed the lter zones corresponding to the neighbouring parts of the layer. By such light diffusions a degradation of colors is eiected so that the colors may not be reproduced with the same saturation as they havein nature. v l

When now the central zone 1s .much smaller r than thelateral ones the color of this zone shows 10- a much greater loss of saturation than the other colors. I

Besides, the longest zone of the projection screen too had to be much smaller than the other zones when it was green or blue vin order to preventfitfrom prevailing;

Now it could be proved that red always too Weak in the projection of lenticular lms whenthe zones are` of about equal areas. This is especially which are necessary for aluminous projection in the great cinemas.' This drawback can not be overcome by using a thinner red-filter, as the red dyes become brown when they are too much diluted, so that it is no longer possible to reproducev a satisfactory red. This fault is especially striking when high intensity arc lamps are employed as these lamps generally have a spectrum I of about equal energy for all wave-lengths in contradiction to most other light-sources which are most eflicient for the longer' wa've lengths.

' It may easily be seen that all these difficulties may be overcome by choosing red for the/zone of the greatest length as this zone may have a greater area than the other ones, thus enabling to give to all zones about the same breadth. The advantages of such screens" are less degradations of color and the possibility of 'employing high intensity arc lamps for the projection without being obliged to waste the higher luminosity of 40 suchlamps by employing iilters absorbing a greater quantity of blue and green in the screen.

When the color zones are not limited by straight lines perpendicular 'to the stripes which form the the case when high intensity arc lamps are used. 20

said zones, the average length of such a zone is calculatedfin the following manner:

It is divided into a great number of small strips o'f equal breadth and 4running in parallel to. the borders between the zones, which direction is gen- .erally also parallel to the direction of the cylindrically shapedilenticular elements .on the lm.

. The lengthsof all these strips are measured and summed up. The sum is! divided with the number of the strips from which results the average length of the zone in consideration. ,The n the of the spectrum, said lter comprising three zones extending generally parallel to the lenticulations on the films, the lter being circular and the zones being colored green, red, and blue, with the red zone extending substantially diametrically across the lter, and the green and blue zones being disposed generally parallel to the red zone and on 5 opposite sides thereof. v

EDGAR GRETENER. 

